Document topology aware volume binding feature

kubernetes · Sep 7, 2018 · 6975125 · 6975125
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diff --git a/content/en/docs/concepts/storage/dynamic-provisioning.md b/content/en/docs/concepts/storage/dynamic-provisioning.md
@@ -124,6 +124,13 @@ Note that there can be at most one *default* storage class on a cluster, or
 a `PersistentVolumeClaim` without `storageClassName` explicitly specified cannot
 be created.
 
+## Topology Awareness
+
+In [multi-zone](/docs/setup/multiple-zones) clusters, pods can be spread across
+zones and single-zone storage backends should be provisioned in the zones where
+pods are scheduled. This can be accomplished by setting the [volume binding
+mode](/docs/concepts/storage/storage-classes/#volume-binding-mode).
+
 {{% /capture %}}
 
 
diff --git a/content/en/docs/concepts/storage/storage-classes.md b/content/en/docs/concepts/storage/storage-classes.md
@@ -57,6 +57,7 @@ parameters:
 reclaimPolicy: Retain
 mountOptions:
   - debug
+volumeBindingMode: Immediate
 ```
 
 ### Provisioner
@@ -66,15 +67,15 @@ for provisioning PVs. This field must be specified.
 
 | Volume Plugin        | Internal Provisioner| Config Example                       |
 | :---                 |     :---:           |    :---:                             |
-| AWSElasticBlockStore | &#x2713;            | [AWS](#aws)                          |
+| AWSElasticBlockStore | &#x2713;            | [AWS EBS](#aws-ebs)                          |
 | AzureFile            | &#x2713;            | [Azure File](#azure-file)            |
 | AzureDisk            | &#x2713;            | [Azure Disk](#azure-disk)            |
 | CephFS               | -                   | -                                    |
 | Cinder               | &#x2713;            | [OpenStack Cinder](#openstack-cinder)|
 | FC                   | -                   | -                                    |
 | FlexVolume           | -                   | -                                    |
 | Flocker              | &#x2713;            | -                                    |
-| GCEPersistentDisk    | &#x2713;            | [GCE](#gce)                          |
+| GCEPersistentDisk    | &#x2713;            | [GCE PD](#gce-pd)                          |
 | Glusterfs            | &#x2713;            | [Glusterfs](#glusterfs)              |
 | iSCSI                | -                   | -                                    |
 | Quobyte              | &#x2713;            | [Quobyte](#quobyte)                  |
@@ -120,6 +121,73 @@ If the volume plugin does not support mount options but mount options are
 specified, provisioning will fail. Mount options are not validated on either
 the class or PV, so mount of the PV will simply fail if one is invalid.
 
+### Volume Binding Mode
+
+{{< feature-state for_k8s_version="v1.12" state="beta" >}}
+
+**Note:** This feature requires the `VolumeScheduling` feature gate to be
+enabled.
+
+The `volumeBindingMode` field controls when [volume binding and dynamic
+provisioning](/docs/concepts/storage/persistent-volumes/#provisioning) should occur.
+
+By default, the `Immediate` mode indicates that volume binding and dynamic
+provisioning occurs once the Persistent Volume Claim is created. For storage
+backends that are topology-constrained and not globally accessible from all nodes
+in the cluster (for example, a zonal disk, or a local volume), this causes
+volumes to be bound or provisioned without knowledge of the pod's scheduling
+requirements, and can result in unschedulable pods.
+
+To address this issue, the `WaitForFirstConsumer` mode can be specified which
+will delay binding and provisioning until a pod using the PVC is created.
+Volumes will be selected or provisioned with the appropriate topology that is
+compatible with the pod's scheduling constraints, including but not limited to, [resource
+requirements](/docs/concepts/configuration/manage-compute-resources-container),
+[node selectors](/docs/concepts/configuration/assign-pod-node/#nodeselector),
+[pod affinity and
+anti-affinity](/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity),
+and [taints and tolerations](/docs/concepts/configuration/taint-and-toleration).
+
+The following plugins support `WaitForFirstConsumer` with dynamic provisioning:
+* [AWSElasticBlockStore](#aws-ebs)
+* [GCEPersistentDisk](#gce-pd)
+* [AzureDisk](#azure-disk)
+
+The following plugins support `WaitForFirstConsumer` with pre-created PV binding:
+* All of the above
+* [Local](#local)
+
+### Allowed Topologies
+{{< feature-state for_k8s_version="v1.12" state="beta" >}}
+
+**Note:** This feature requires the `VolumeScheduling` feature gate to be
+enabled.
+
+When `WaitForFirstConsumer` volume binding mode is specified, it is no longer necessary
+to restrict provisioning to specific topologies in most situations. However,
+if still required, `allowedTopologies` can be specified.
+
+This example demonstrates how to restrict topology of provisioned volumes to specific
+zones and should be used as a replacement for the `zone` and `zones` parameters for the
+supported plugins.
+
+```yaml
+kind: StorageClass
+apiVersion: storage.k8s.io/v1
+metadata:
+  name: standard
+provisioner: kubernetes.io/gce-pd
+parameters:
+  type: pd-standard
+volumeBindingMode: WaitForFirstConsumer
+allowedTopologies:
+- matchLabelExpressions:
+  - key: failure-domain.beta.kubernetes.io/zone
+    values:
+    - us-central1-a
+    - us-cetnral1-b
+```
+
 ## Parameters
 
 Storage classes have parameters that describe volumes belonging to the storage
@@ -128,7 +196,7 @@ class. Different parameters may be accepted depending on the `provisioner`. For
 `iopsPerGB` are specific to EBS. When a parameter is omitted, some default is
 used.
 
-### AWS
+### AWS EBS
 
 ```yaml
 kind: StorageClass
@@ -138,17 +206,16 @@ metadata:
 provisioner: kubernetes.io/aws-ebs
 parameters:
   type: io1
-  zones: us-east-1d, us-east-1c
   iopsPerGB: "10"
 ```
 
 * `type`: `io1`, `gp2`, `sc1`, `st1`. See
   [AWS docs](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html)
   for details. Default: `gp2`.
-* `zone`: AWS zone. If neither `zone` nor `zones` is specified, volumes are
+* `zone` (Deprecated): AWS zone. If neither `zone` nor `zones` is specified, volumes are
   generally round-robin-ed across all active zones where Kubernetes cluster
   has a node. `zone` and `zones` parameters must not be used at the same time.
-* `zones`: A comma separated list of AWS zone(s). If neither `zone` nor `zones`
+* `zones` (Deprecated): A comma separated list of AWS zone(s). If neither `zone` nor `zones`
   is specified, volumes are generally round-robin-ed across all active zones
   where Kubernetes cluster has a node. `zone` and `zones` parameters must not
   be used at the same time.
@@ -164,7 +231,10 @@ parameters:
   encrypting the volume. If none is supplied but `encrypted` is true, a key is
   generated by AWS. See AWS docs for valid ARN value.
 
-### GCE
+**Note:** `zone` and `zones` parameters are deprecated and replaced with
+[allowedTopologies](#allowed-topologies)
+
+### GCE PD
 
 ```yaml
 kind: StorageClass
@@ -174,15 +244,14 @@ metadata:
 provisioner: kubernetes.io/gce-pd
 parameters:
   type: pd-standard
-  zones: us-central1-a, us-central1-b
   replication-type: none
 ```
 
 * `type`: `pd-standard` or `pd-ssd`. Default: `pd-standard`
-* `zone`: GCE zone. If neither `zone` nor `zones` is specified, volumes are
+* `zone` (Deprecated): GCE zone. If neither `zone` nor `zones` is specified, volumes are
   generally round-robin-ed across all active zones where Kubernetes cluster has
   a node. `zone` and `zones` parameters must not be used at the same time.
-* `zones`: A comma separated list of GCE zone(s). If neither `zone` nor `zones`
+* `zones` (Deprecated): A comma separated list of GCE zone(s). If neither `zone` nor `zones`
   is specified, volumes are generally round-robin-ed across all active zones
   where Kubernetes cluster has a node. `zone` and `zones` parameters must not
   be used at the same time.
@@ -199,6 +268,9 @@ specified, Kubernetes will arbitrarily choose among the specified zones. If the
 `zones` parameter is omitted, Kubernetes will arbitrarily choose among zones
 managed by the cluster.
 
+**Note:** `zone` and `zones` parameters are deprecated and replaced with
+[allowedTopologies](#allowed-topologies)
+
 ### Glusterfs
 
 ```yaml
@@ -678,4 +750,4 @@ Delaying volume binding allows the scheduler to consider all of a pod's
 scheduling constraints when choosing an appropriate PersistentVolume for a
 PersistentVolumeClaim.
 
-{{% /capture %}}
+{{% /capture %}}
diff --git a/content/en/docs/reference/command-line-tools-reference/feature-gates.md b/content/en/docs/reference/command-line-tools-reference/feature-gates.md
@@ -56,7 +56,7 @@ different Kubernetes components.
 | `DevicePlugins` | `true` | Beta | 1.10 | |
 | `DynamicKubeletConfig` | `false` | Alpha | 1.4 | 1.10 |
 | `DynamicKubeletConfig` | `true` | Beta | 1.11 | |
-| `DynamicProvisioningScheduling` | `false` | Alpha | 1.11 | |
+| `DynamicProvisioningScheduling` | `false` | Alpha | 1.11 | 1.11 |
 | `DynamicVolumeProvisioning` | `true` | Alpha | 1.3 | 1.7 |
 | `DynamicVolumeProvisioning` | `true` | GA | 1.8 | |
 | `EnableEquivalenceClassCache` | `false` | Alpha | 1.8 | |

diff --git a/content/en/docs/setup/multiple-zones.md b/content/en/docs/setup/multiple-zones.md
@@ -72,18 +72,20 @@ available and can tolerate the loss of a zone, the control plane is
 located in a single zone.  Users that want a highly available control
 plane should follow the [high availability](/docs/admin/high-availability) instructions.
 
+### Volume limitations
+The following limitations are addressed with [topology-aware volume binding](/docs/concepts/storage/storage-classes/#volume-binding-mode).
+
 * StatefulSet volume zone spreading when using dynamic provisioning is currently not compatible with
-pod affinity or anti-affinity policies.
+  pod affinity or anti-affinity policies.
 
 * If the name of the StatefulSet contains dashes ("-"), volume zone spreading
-may not provide a uniform distribution of storage across zones.
+  may not provide a uniform distribution of storage across zones.
 
 * When specifying multiple PVCs in a Deployment or Pod spec, the StorageClass
-needs to be configured for a specific, single zone, or the PVs need to be
-statically provisioned in a specific zone. Another workaround is to use a
-StatefulSet, which will ensure that all the volumes for a replica are
-provisioned in the same zone.
-
+  needs to be configured for a specific, single zone, or the PVs need to be
+  statically provisioned in a specific zone. Another workaround is to use a
+  StatefulSet, which will ensure that all the volumes for a replica are
+  provisioned in the same zone.
 
 ## Walkthrough